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authorMikael Starvik <mikael.starvik@axis.com>2005-07-27 11:44:44 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-07-27 16:26:01 -0700
commit51533b615e605d86154ec1b4e585c8ca1b0b15b7 (patch)
tree4a6d7d8494d2017632d83624fb71b36031e0e7e5 /arch/cris/arch-v32/lib/checksum.S
parent5d01e6ce785884a5db5792cd2e5bb36fa82fe23c (diff)
[PATCH] CRIS update: new subarchitecture v32
New CRIS sub architecture named v32. From: Dave Jones <davej@redhat.com> Fix swapped kmalloc args Signed-off-by: Mikael Starvik <starvik@axis.com> Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/cris/arch-v32/lib/checksum.S')
-rw-r--r--arch/cris/arch-v32/lib/checksum.S111
1 files changed, 111 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/lib/checksum.S b/arch/cris/arch-v32/lib/checksum.S
new file mode 100644
index 000000000000..32e66181b826
--- /dev/null
+++ b/arch/cris/arch-v32/lib/checksum.S
@@ -0,0 +1,111 @@
+/*
+ * A fast checksum routine using movem
+ * Copyright (c) 1998-2001, 2003 Axis Communications AB
+ *
+ * csum_partial(const unsigned char * buff, int len, unsigned int sum)
+ */
+
+ .globl csum_partial
+csum_partial:
+
+ ;; r10 - src
+ ;; r11 - length
+ ;; r12 - checksum
+
+ ;; check for breakeven length between movem and normal word looping versions
+ ;; we also do _NOT_ want to compute a checksum over more than the
+ ;; actual length when length < 40
+
+ cmpu.w 80,$r11
+ blo _word_loop
+ nop
+
+ ;; need to save the registers we use below in the movem loop
+ ;; this overhead is why we have a check above for breakeven length
+ ;; only r0 - r8 have to be saved, the other ones are clobber-able
+ ;; according to the ABI
+
+ subq 9*4,$sp
+ subq 10*4,$r11 ; update length for the first loop
+ movem $r8,[$sp]
+
+ ;; do a movem checksum
+
+_mloop: movem [$r10+],$r9 ; read 10 longwords
+
+ ;; perform dword checksumming on the 10 longwords
+
+ add.d $r0,$r12
+ addc $r1,$r12
+ addc $r2,$r12
+ addc $r3,$r12
+ addc $r4,$r12
+ addc $r5,$r12
+ addc $r6,$r12
+ addc $r7,$r12
+ addc $r8,$r12
+ addc $r9,$r12
+
+ ;; fold the carry into the checksum, to avoid having to loop the carry
+ ;; back into the top
+
+ addc 0,$r12
+ addc 0,$r12 ; do it again, since we might have generated a carry
+
+ subq 10*4,$r11
+ bge _mloop
+ nop
+
+ addq 10*4,$r11 ; compensate for last loop underflowing length
+
+ movem [$sp+],$r8 ; restore regs
+
+_word_loop:
+ ;; only fold if there is anything to fold.
+
+ cmpq 0,$r12
+ beq _no_fold
+
+ ;; fold 32-bit checksum into a 16-bit checksum, to avoid carries below.
+ ;; r9 and r13 can be used as temporaries.
+
+ moveq -1,$r9 ; put 0xffff in r9, faster than move.d 0xffff,r9
+ lsrq 16,$r9
+
+ move.d $r12,$r13
+ lsrq 16,$r13 ; r13 = checksum >> 16
+ and.d $r9,$r12 ; checksum = checksum & 0xffff
+ add.d $r13,$r12 ; checksum += r13
+ move.d $r12,$r13 ; do the same again, maybe we got a carry last add
+ lsrq 16,$r13
+ and.d $r9,$r12
+ add.d $r13,$r12
+
+_no_fold:
+ cmpq 2,$r11
+ blt _no_words
+ nop
+
+ ;; checksum the rest of the words
+
+ subq 2,$r11
+
+_wloop: subq 2,$r11
+ bge _wloop
+ addu.w [$r10+],$r12
+
+ addq 2,$r11
+
+_no_words:
+ ;; see if we have one odd byte more
+ cmpq 1,$r11
+ beq _do_byte
+ nop
+ ret
+ move.d $r12,$r10
+
+_do_byte:
+ ;; copy and checksum the last byte
+ addu.b [$r10],$r12
+ ret
+ move.d $r12,$r10